ext2 question

Manfred Spraul (manfreds@colorfullife.com)
Sat, 15 May 1999 20:45:06 +0200

ext2 uses an array (direct, double indirect, tripple indirect) to store
the blocks that belong to a file. Every array field stores 1 block, i.e.
additional disk accesses are required if the file is > 12 kB even if the
file is not fragmented.
Most other modern filesystems (Be FS, Hfs, Hfs Extended, NTFS, HPFS)
use a btree/list/compressed list of (start+len) to store this
information.

Are there any plans to support to a (start+len) system?

Perhaps we could replace the 12 direct blocks with 8 direct extents (4
byte start + 2 byte len), while keeping the current system for the
contents of the indirect blocks:
This would ensure that for 99,99% of all files no indirect blocks are
required, but we would avoid a long linear search for highly
fragmented/very long files.

--
	Manfred




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